1. Field of the invention
The invention concerns a torsional damper device for torque transmission systems, such as clutches, of the type comprising two coaxial parts respectively cooperating with circumferentially acting springs to absorb variations in the torque.
The invention is more particularly concerned with the structure of engagement means between one of the coaxial parts and pivoting base members on which said springs are mounted.
2. Description of the prior art
A torque transmission system such as a friction clutch designed to be inserted between the crankshaft of the motor and the input shaft of the gearbox in an automobile vehicle usually comprises a torsional damper device adapted to absorb variations in this torque to avoid vibration and in particular audible vibration arising at any point along the kinematic system in which said torsional damper device is inserted. A damper device of this kind is often combined with the friction disk of the clutch or with the inertia flywheel driven by the crankshaft of the motor and also serving as a reaction plate for the clutch.
French patent No. 2 571 461 describes a torsional damper device of this kind combined with an inertia flywheel. The flywheel comprises two coaxial parts between which are circumferentially disposed helical coil springs. To be more precise, each spring is held between base members pivotally mounted between two flanges (also called guide rings) of a first part, in this instance the driving part, while the same base members are adapted to be loaded circumferentially with the possibility of articulation by annular metal plates fastened to the driven part, variation in the compression of the springs absorbing variations in torque and procuring some degree of filtering of vibrations of all kinds.
Two parallel plates are provided, at a short axial distance from each other, this arrangement forming a torque limiter.
This assembly gives good results, principally because of the inclusion of the pivoted base members which enable the springs to function under optimum conditions by preventing them being subjected to excessive radial deformation inwards or outwards. The base members are molded from a relatively rigid plastics material.
However, it has been noticed that under certain operating conditions the two plates aforementioned could become offset circumferentially and not enter simultaneously into contact with the base members. Apart from incorrect functioning of the springs, this can lead to deterioration of these base members. This malfunctioning can go so far as to result in skewing of a base member, leading to its rapid destruction. An object of the invention is to resolve this difficulty.